Question: How to plot a vertical plane with a curved top

I tried this, but it doesn't seem to like having the x's and y's in the z range. 

 implicitplot3d(x = 6, x = 1 .. 7, y = 2 .. 5, z = 0 .. (1/4)*(x-4)^2+(1/5)*(y-3)^2+10
  , view = [0 .. 8, 0 .. 8, 0 .. 20], transparency = .5, style = hidden);
%;
Error, (in plots/iplot3d/implicit3d) bad range arguments x = 1 .. 7, y = 2 .. 5, z = 0 .. (1/4)*(x-4)^2+(1/5)*(y-3)^2+10

I'm trying to plot a surface above the xy plane that looks like a solid, but I don't want black grid or "wireframe" lines.  style=hidden causes the grid lines to be light coloured, which is what I want, but "sytle" doesn't seem to  work when filled=true, so I am trying to plot the planes that make up the sides of the solid with separate commands.  

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